Building Energy Efficiency

Studies show that people can tolerate elevated temperatures in the presence of appreciable air movement (e.g., from using ceiling fans). This minimises the use of air-conditioners and extends their set-point temperature ($T_{set}$), resulting in energy savings in space cooling. However, there is little empirical evidence on the energy savings from using ceiling fans with Room Air-Conditioners (RACs). To address this gap, we analysed the energy performance of RACs with both fixed-speed compressors and inverter technology at different set-point temperatures and ceiling fan speed settings in 15 residential Mixed-Mode Buildings (MMBs) in India. Thermal comfort conditions (as predicted by the Indian Model for Adaptive Comfort-Residential (IMAC-R)) with minimum energy consumption were maintained at a set-point temperature ($T_{set}$) of 28 and 30 ${}^{\circ }$C and a fan speed setting of one. Compared with a $T_{set}$ of 24 ${}^{°}$C, a $T_{set}$ of 28 and 30 ${}^{°}$C resulted in energy savings of 44 and 67%, respectively. With the use of RACs, a configuration with a minimum fan speed was satisfactory for an optimal use of energy and for maintaining the conditions of thermal comfort. In addition, RACs with inverter technology used 34–68% less energy than fixed-speed compressors. With the rising use of RACs, particularly in tropical regions, the study’s outcomes offer a significant potential for reducing space-cooling energy consumption and the resultant greenhouse gas (GHG) emissions. Full article

The built environment contributes to 35% of the global energy consumption and 38% of energy-related carbon emissions. The exponential population growth, coupled with the inability of the existing building stock to meet demands or reach the end of its lifespan, has precipitated the proliferation of new constructions worldwide. However, it has been proven well that retrofitting existing buildings might impact the environment less, save resources, and reduce the carbon footprint while extending their lifecycle. Various techniques are available to assess the performance of existing buildings and quantify the energy-saving potential of renovation measures. Building information modeling (BIM) technology serves as a virtual laboratory for buildings and can be used to model building stocks and measure how building performance changes with alternative envelope and system proposals. This research study explores the potential of BIM-based energy modeling to evaluate the effectiveness of refurbishment scenarios on a residential building. A total of 192 alternative scenarios were developed by considering six variables (wall, roofing, insulation, glazing, lighting power density, and photovoltaic panels). The results were analyzed across annual energy consumption (fuel and electric), annual/lifecycle energy costs, energy use intensity, annual CO₂ emissions, and initial investment costs. The optimum alternative scenario decreased the annual fuel and electricity consumption of the sample building by 61% and 64%, respectively. The payback period was calculated as 12 years. This study demonstrates the impact of BIM in enhancing the energy efficiency of the existing building stock, presenting results within the context of a residential building. Full article

This research provides a comprehensive exploration of energy efficiency dynamics in non-residential public buildings such as schools, swimming pools, hospitals, and museums. Recognizing the distinct energy consumption patterns of each building type, the study accentuates the unique challenges they present, with a particular focus on the continuous and intensive energy demands of hospitals and the unparalleled energy needs of swimming pools. Through an extensive review of various case studies, the research unveils prevailing energy consumption trends, highlighting the role of metrics in assessing energy efficiency and the inherent challenges these metrics face in ensuring uniformity and direct comparability. A core element of this analysis emphasizes the dual nature of technical retrofitting, categorizing interventions into passive and active measures. The research delves into the sustainability imperatives of energy interventions, exploring the economic motivations underpinning retrofit decisions, and the intricate relationship between advanced technological solutions and the behavioral tendencies of building operators and users. Additionally, the study uncovers the influence of external determinants such as climatic factors and government policies in shaping energy consumption in public buildings. In synthesizing these findings, the paper offers insightful recommendations, emphasizing the need for an integrated approach that harmonizes technological innovations with informed operational habits, aiming to optimize energy efficiency in public non-residential buildings. Full article

As a type of passive architectural structure, wall-mounted solar chimneys enhance the natural ventilation volume of a building’s interior, and maximize reductions in the building’s operational energy consumption. They are indispensable in the building’s energy conservation and emission reduction. Therefore, measuring the wall-mounted solar chimney’s flow characteristics and relevant index parameters is particularly important. This paper uses a combination of full-scale experiments and numerical simulation to conduct a detailed analysis of the wall-mounted solar chimney. Four different radiation models, namely DO (discrete ordinates), S2S (surface-to-surface), MC (Monte Carlo), and Rosseland are used for comparison, and the results of the numerical simulation are compared with the experimental data. The results show that the maximum turbulent viscosity of the fluid predicted by the S2S radiation model is higher than that of the MC and DO models by 16.87% and 8.44%, respectively. The errors of the DO radiation model in the midline and glass cover plate direction concerning the experimental results are only 0.33% and 0.15%, respectively. The mistakes of the MC radiation model in these two directions are 0.51% and 0.47%, respectively. The DO radiation model is more suitable in numerical simulation predictions related to the wall-mounted solar chimney. Full article

This paper presents the results of a study that developed improved inverse models to accurately predict the annual daylighting performance (sDA and lighting energy use) of various window configurations. This inverse model is an improvement over previous inverse models because it can be applied to variable room geometries at different weather locations in the US. The room geometries can be varied from 3 m × 3 m × 2.5 m to 15 m × 15 m × 10 m (length × width × height). The other variables used in the model include orientation (N, E, S, W), window-to-floor ratio, window location in the exterior wall, glazing visible transmittance, ceiling visible reflectance, wall visible reflectance, shade type (overhangs, fins), shade visible reflectance, lighting power density (LPD) (W/m²), and lighting dimming setpoint (lux). Such models can quickly advise architects during the preliminary design phase about which daylighting design options provide useful daylighting, while minimizing the annual auxiliary lighting energy use. The inverse models tested and developed were multi-linear regression (MLR) models, which were trained and tested against Radiance-based annual daylighting simulation results. In the analysis, 482 cases with different model conditions were simulated, to develop and validate the inverse models. This study used 75% of the data to train the model and 25% of the data to validate the model. The results showed that the new inverse models had a high accuracy in the annual daylighting performance predictions, with an R² of 0.99 and an CV(RMSE) of 15.19% (RMSE of 58.91) for the lighting energy (LE) prediction, and an R² of 0.95 and an CV(RMSE) of 14.38% (RMSE of 8.02) for the sDA prediction. In addition, the validation results showed that the LE MLR model and sDA MLR model had an R² of 0.96 and 0.85, and RASE of 121.89 and 8.54, respectively, which indicate that the inverse models could accurately predict daylighting results for sDA and lighting energy use. Full article

Single-side natural ventilation is a commonly used means of ventilation to effectively regulate the thermal environment in building interiors without any fossil energy consumption. To achieve most of the potential for the efficiency of single-side natural ventilation, research needs to be undertaken into the forces that drive single-side natural ventilation. This paper examines the single-side natural ventilation of a single vertical single opening (SSO) and a vertical double opening (SDO) in a freestanding building under wind and thermal pressure. The change in the trajectory of vortex shedding when the building is leeward as well as the frequency of vortex shedding in square buildings was investigated by large eddy simulation (LES), and computational fluid dynamics was used to analyze the difference in the air exchange rate of single-side natural ventilation of SSO and SDO in the windward and leeward conditions of the building. Both of these methods were used in conjunction with one another. According to the findings, the creation of vortices at SSO and SDO in the presence of low wind speeds reduces the ventilation effect of thermal pressure under windward circumstances. Consequently, the influence of thermal stress and wind stress ultimately cancel each other out, and this phenomenon finally disappears as the wind blowing from the outside of the structure increases. The shedding of vortices in the leeward state accomplishes a form of air supply pumping with a particular periodicity of airflow fluctuations in the lateral direction. The Strouhal number computed using the LES simulation acts in a manner consistent with the experimental findings. Full article

The aim of this research was to analyze the drivers and barriers facing the agents involved in the energy renovation process and the effective use of existing subsidies for this purpose. The drive for energy renovation in buildings is undeniable. European policies aiming to completely decarbonize the economy by 2050 will give an important boost to the building sector in Europe by improving comfort conditions in renovated homes. In this study, a questionnaire was developed using the free software LimeSurvey, which was then evaluated by experts. The questionnaire included representative indicators of energy refurbishment and was segmented into the intervening groups to highlight their differences. The results were analyzed using the Mann–Whitney test for group comparisons and Pearson’s correlation coefficient to assess the relationships between the responses. This analysis reveals the complexity of a process, in which excessive bureaucratic requirements to obtain Next Generation EU funds, economic aspects (80%) and owners’ lack of awareness are the barriers that were most highlighted by those surveyed (77%). In terms of motivation, we found that, apart from economic savings (88%), the most valued aspect for users was noise insulation (93%), which is not directly related to energy improvement. This study highlights the lack of knowledge and information that the agents responsible for this change have about energy improvement and their differences in opinions on motivations and barriers. Full article

The air conditioning demand varies significantly in the hot and desert climates of the UAE due to diurnal temperature variation, seasonal shifts, and occupancy patterns. One of the challenges faced by the relatively higher energy-consuming UAE building stock is to optimize cooling capacity utilization and prevent excessive energy loss due to undesired cooling. A potential route to achieving such a goal involves cooling energy storage during low demand and releasing the stored cooling at peak demand times via thermal energy storage (TES). Latent heat thermal energy storage (LHTES) employing phase change materials (PCMs) provides impactful prospects for such a scheme, thus gaining tremendous attention from the scientific community. The primary goal of the current article is to provide a comprehensive state-of-the-art literature review on PCM-based TES for cooling applications to understand its efficacy, limitations, and future prospects. The article involves various applications, designs, and validations. The article emphasizes the importance of material innovations and heat transfer augmentation strategies to render this technology feasible for real-life integration into cooling systems. Full article

In the context of global warming and the energy crisis, a large amount of energy consumed by the construction industry has a negative impact on climate change. Green retrofitting for older multi-story houses can significantly reduce energy consumption and pollutant gas emissions. However, a comprehensive evaluation method is needed to select suitable retrofitting methods. This paper established a green renovation evaluation system, including five dimensions from the green concept, and 16 evaluation indexes. Making an old multi-story house in Shenyang the research object, 16 transformation plans were generated through orthogonal experiments. The total weights of each index were derived through entropy weighting and expert scoring, and then the best retrofit solution was selected using the improved TOPSIS method. The best retrofit solution was evaluated to reduce energy consumption by 3016.4 kWh/m² and pollutant gas emissions by 3934.3 tons over the remaining 35 years of its life cycle while generating an economic benefit of approximately 1.58 million yuan. These study results show that the retrofitting of external walls significantly affects the building’s energy consumption; exterior windows present the most negligible impact. The photovoltaic facilities provide significant energy savings. Full article

Energy demand for active mechanical space cooling is projected to double by 2050. Wider adoption of passive cooling systems can help reduce demand. However, familiarity with these systems remains low, and innovation in the field is constrained due to a lack of cost-effective, accessible performance evaluation methods. This paper reports the design, construction, and commissioning of an affordable, self-contained environmental test chamber. The novel chamber replicates a range of outdoor conditions common in hot, dry regions, making possible year-round testing of reduced-scale prototypes. Data from calibration testing are reported, showing no significant difference in evaporative efficiency when a reduced-scale prototype tested in the chamber is compared with datasets from prior full-scale testing. Analyzing the results using an independent sample two-tailed t-test with a 95% confidence interval found a p-value of 0.75. While measured outlet air velocities for reduced-scale and full-scale prototypes differed to some extent (root mean square error of 0.45 m/s), results were nevertheless deemed comparable due to errors introduced by the rapid change in wind speeds and directions at full scale. Future chamber modifications will correct misalignments between data collected from the two scales and prevent observed increases in the chamber’s relative humidity levels during testing. Full article

In this paper, we present the final results from the research project “Urban Abacus of Building Energy Performances (Abaco Urbano Energeticodegli Edifci–AUREE)” aimed at supporting the renovation process and energy efficiency enhancement of urban building stocks. The crux of the AUREE project is a Web–GIS GeoBlog portal with customized semantic dashboards aimed at sharing information on an urban built environment and promoting the participation of local stakeholders in its improvement. As the latest development of this research, a workflow that integrates the AUREE portal with BIM authoring and an open-source IoT platform is implemented and applied to an experimental case study concerning a public building in Carbonia (Italy). The headquarters of the Sotacarbo Sustainable Energy Research Center was selected as the case study. The presented results proved that it was possible to create a valid open system, which was accessible to both specialist and unskilled users, and aimed at guiding, through a progressive knowledge deepening, common end-users toward proper conscious “energy behaviors” as well as public administrations and decision-makers toward sustainable facility management. Later, the proposed open system could also be suitable to be used as an effective tool to support the rising “energy communities”. Full article

Space heating accounts for a large part of building energy consumption. Lowering the heating temperature set-point (Tsp) is expected to be a feasible approach for energy efficiency. In this paper, eight globally typical cities are selected, and the energy-saving mechanism and variation trends of lowering heating Tsp are investigated under different working conditions (climate conditions, construction completion year and inner heat sources). The results show that significant energy-saving effects even appear in the relatively warm-winter cities. The energy-saving mechanism is dominated by two different categories of heating hours including the temperature-difference saving (TDS) hours and the behavioral saving (BS) hours. The contribution of TDS and BS to the whole annual heating energy saving amount (HSA) depends on the reducing level of heating hours. The HSA of lowing Tsp is mainly affected by TDS influence. After coupling the consideration of different factors, with the decreasing annual HSA of buildings, the dominance of the TDS influence mechanism shrinks gradually while the annual heating energy saving ratio (HSR) increases. This work provides the analysis method for building heating energy saving potential evaluation and reference for the establishment of standards and residents’ behavioral energy saving in different climatic zones. Full article

Numerous experiments have shown that trees can reduce the energy consumption of adjacent buildings, but little research has been carried out on how leaf area density (LAD) and the distance between walls and trees (D_W-T) in different orientations affect the energy consumption of rural houses. Using an investigation method, a simulation method, and a remote sensing information extraction method, the impact of different tree-planting scenarios on the energy consumption of typical rural houses was analyzed. The results show that the energy-saving effect becomes more prominent with a higher leaf area density of trees in summer. Under the same conditions, Osmanthus fragrans is the most effective tree, followed by Koelreuteria paniculata, and then pomegranate. Moreover, the energy-saving rate of the rural house increases with a decrease in the wall–crown distance of the tree. For instance, when a Koelreuteria paniculata is planted on the west side of the rural house with a wall–crown distance of 1–3 m, the energy-saving rate ranges from 4.38% to 9.81%. Additionally, the planting orientation of the tree affects the energy-saving rate, with the west-facing orientation being the best and the north-facing orientation being the worst under the same conditions, and the energy-saving rate of the best orientation (west-facing) ranging from 2.11% to 14.98%. By establishing a comprehensive model, it was found that planting Osmanthus fragrans on the west side of a rural house with a 1 m wall–crown distance yields the best energy-saving effect. The results of this study can provide theoretical support for planting trees around rural houses from the perspective of energy saving. Full article

According to the World Economic Forum, the building sector is responsible for 40% of global energy consumption and 33% of greenhouse gas (GHG) emissions, and this is expected to increase due to population growth and the subsequent impact on the environment, economy and health. To tackle the problem, countries have set new construction codes, policies and regulations for the construction of new buildings in an effort to make them greener. However, there is a need to enhance the status of the existing buildings, especially mosques, as they are the main contributors to energy usage and water consumption in the United Arab Emirates (UAE). Therefore, this research seeks to fill this gap, aiming to evaluate the energy usage and water consumption practices employed in the existing mosque buildings within the UAE and to provide recommendations for improving the sustainability of mosques, with a focus on the environmental and economic pillars. The methodology relies mainly on data collected from 146 existing mosque buildings that have undergone energy saving audits across the UAE. Descriptive statistical analysis is performed to analyze the data from the period of 2018–2019 in order to determine the most significant factors related to energy inefficiency in existing mosque buildings in the UAE and to determine the most cost-effective and energy-saving corrective measures for energy and water conservation. The findings further enhance the standard of experience for mosque visitors (social aspect); reduce energy bill expenses, providing an acceptable return on investment from the proposed energy conservation measures for stakeholders (economic); and reduce the overall energy consumption, which can reduce the total CO₂ emissions from mosque buildings (environmental). Full article

The possibilities of obtaining efficient building thermal control by means of colored envelopes while maintaining broad aesthetic options have been evaluated. The use of colored bilayers, where the inner layer presents strong solar absorbent or reflectance properties, while the outer layer provides visible coloration, represents a feasible way. A representative set of twenty bilayers spanning a broad color palette has been studied in two configurations, static and dynamic. The dynamic configuration allows for the switching of the inner layer between absorptive and reflective states. Simulations have been carried out in a total of nineteen locations around the world, representing the main habitable climates according to Köppen–Geiger climate classification. Comparative results between climate zones where this approach may have a significant impact have been obtained, and identification of feasible climate zones has been carried out. The use of the simpler static configuration is recommended for tropical climates, whereas the dynamic configuration could be effective in moderate climate locations (within arid or temperate climate classification). Possible savings for cold climates are negligible. Full article

The 150 cm tall windows that used as the standard in residential buildings are now being replaced by 220 cm tall windows, which are rapidly becoming widespread. This study examined different window types according to both the type of glass used as well as the type of fill material used in double-glazed windows in order to show the effect of window selection on the energy consumption of the building. A comparison between Antalya and Erzurum was also made in the study. The study was carried out on a building model with seven floors and twenty-four apartments, each of which has five units. The window heights in each unit were assumed to be 150 cm and were defined as Type 0. Five additional building types were defined by increasing the window heights in each unit, respectively. Thermal load values were calculated for all six building types and compared with each other. As a result, a 46.7% increase in the window area causes a maximum heat loss of 9.6% in Erzurum and a maximum heat gain of 45.1% in Antalya. These values bring about an increase in the energy consumption by an average of USD 1465.32 per year in Erzurum and an average of USD 581.08 per year in Antalya. Full article

In residential buildings, air infiltration impacts energy, indoor air quality, and thermal comfort considerably. While air infiltration in residential buildings has been the focus of many studies, most published field-testing results pertain to developed countries, with little or no data on air infiltration in developing nations. This paper presents the results of one of the first field investigations into envelope infiltration in the residential buildings of the hot-arid climatic area of Egypt. To analyze the air permeability of the building envelope, the fan pressurization method, often known as the blower door test (BDT), is used, following ISO 9772. The study focuses on 20 residential dwellings built with heavy construction materials and subjects them to extensive characterization and testing. The average air leakage and the air permeability rate for the tested sample were 6.14 h⁻¹ and 17.3 m³/(h∙m²), respectively. However, significant variations in airtightness were observed across the dwelling, leading the team to test several building-related parameters statistically to study their impact on airtightness. Fenestration quality appeared to be a critical factor in determining air infiltration, showing a strong correlation with the air change and leakage. A further investigation underscored that the specific aperture factor and the fenestration quality can predict the infiltration rates to a large degree. Thus, we recommend further investigation of these characteristics in heavy construction material building. Finally, we strongly recommend that building codes in developing countries such as Egypt include minimum performance requirements for fenestration. Full article

One of the important factors influencing the thermal performance of buildings is the leakage of the envelope. When it comes to Montenegro, although there is a formal airtightness requirement, air permeability tests are not mandatory and therefore there is a lack of data in this regard. This paper reports the results of fan pressurization tests on a single apartment in a multi-family residential building before and after replacing the windows. The replacement of old wooden windows with new UPVC ones, provided that the installation is carefully supervised, proved to be an effective air tightening measure, as it resulted in a reduction of air change rate at the reference building pressure from 6.25 h⁻¹ to 0.77 h⁻¹, or by nearly 90%. The energy impact of air leakage was evaluated using the national software for calculating the energy performance of buildings based on the DIN V 18599 methodology. Calculations showed that by reducing infiltration, significant energy savings for heating can be achieved, while savings for cooling are practically negligible. Savings in relative terms were greater when the façade walls were thermally insulated and when the building was located in a colder climate zone. Savings in delivered energy ranged from 13 to 25 kWh/m²·year, depending on the climate zone. Full article

In the last decade, green solutions for road tunnels have steadily emerged in the field of engineering. The focus has been on using renewable energy sources to conserve energy and address issues of disaster risk management, territorial resilience and vulnerability, especially as these issues relate to critical infrastructures (CIs), such as roads and railways. Focusing on the equilibrium of the infrastructure through integrated system services and their external effects guarantees a better evaluation of both effects as they relate to other systems and energy consumption optimisation. To this end, a systematic literature review has been conducted herein that collects and analyses studies carried out in the last decade that relate to green energy solutions in tunnels. Upon a review of the Scopus database from 2013 to 2022, 46 conceptual and empirical studies were selected. Classifications and discussions were then developed according to the main issues identified (e.g., energy saving in road tunnels, zero-energy tunnels, renewable energy sources, tunnel safety lighting, and sustainable infrastructure). Each contribution constitutes a part of the current literature that combines the problems of tunnel safety (as represented by the energy costs of safety devices, e.g., tunnel lighting systems) with issues of renewable energy sources in tunnels. The results of this systematic review offer ideas for future directions of the ‘green’ vision for tunnel infrastructure. This study represents the state-of-the-art of renewable energy solutions currently present worldwide. Gaps in the literature that have yet to be addressed include how to build a green system as well as how to balance its life costs. The review supports the claim that the integration of renewable energy sources can exploit innovative solutions related to the concept of resilience. Full article

Approximately 40% of the overall energy consumption of society is consumed by buildings. Most building energy usage is due to poor envelope performance. In regions with cold winters, the corners of structures typically have the lowest interior surface temperature. In corners, condensation, frost, and mold are common. This has a substantial effect on building energy usage and residents’ comfort. In this study, the heat loss of corner envelopes is evaluated, and a suitable insulation construction of wall corners is constructed to increase the surface temperature of the envelope interior. Computational Fluid Dynamics simulation has been used to examine the heat transmission in a corner of an ultra-low energy building in this study. By comparing the indoor surface temperature to the soil temperature beneath the building, the insulation construction of wall corners has been tuned. The study results indicate that the planned insulation construction of wall corners can enhance the internal surface temperature in the corner and the soil temperature under the structure by approximately 8.5 °C, thereby decreasing the indoor–outdoor temperature differential and the heat transfer at ground level. In extremely cold places, the insulation horizontal extension belt installation can help prevent the earth beneath the building from freezing throughout the winter. Full article

During the last decades, attention to energy and environmental problems has significantly grown, along with the development of international and national policies addressing sustainability issues. In the construction sector, one of the most widespread energy efficiency strategies consists of thermal insulation of buildings thanks to external insulating panels. Among these, wood fiber is an insulating material characterized by a natural, eco-sustainable and biodegradable structure, coming from the recycling of waste wood from sawmills. The present study aimed to characterize small test building insulated with wood fiber panels from the thermal point of view, comparing the results with those of an identical, non-insulated reference test building. The experimental campaign highlighted several advantages and an excellent thermal performance provided by the eco-sustainable solution of wood fiber insulating panels: Lower values of the thermal transmittance (−57%), thus ensuring greater stability of the internal air temperature and better values in terms of attenuation (−60% in summer and −74 % in winter) and phase shift (+2 h in summer and +2.28 h in winter) compared to those obtained from the reference building. The material is also equipped with an Environmental Performance Declaration (EPD) that certifies its environmental benefits. Full article

This research presents a comparative study of different bio-sourced and recycled insulation materials and their impact on energy consumption of office buildings located in Ouagadougou, a city with a dry hot climate. A thorough assessment of the country’s meteorological and urban development data from 2004 to 2018 was conducted for climatic data. EnergyPlus was used for thermal comfort based on the American Society of Heating, Refrigerating, and Air-conditioning Engineers Standard (ASHRAE) 55 adaptive comfort model and energy analysis by calculating and comparing the yearly energy consumption, heat transfer through the building envelope, and discomfort degree hours. A four-story “H”-shaped office building made of cement blocks with a fixed north–south orientation and a 30% window-to-wall ratio served as the base case for this study to perform two rounds of multiple simulations and evaluate the most effective insulation material. First, exterior walls were insulated, and then the roof and inner floors were insulated using the best material from the first round. The findings confirmed hemp wool as the best performing bio-sourced insulation material, which reduces by 25.8% and 17.7% the annual cooling energy demand at 114,495 kWh and the annual energy consumption at 203,598 kWh, respectively, contributing to saving up to 43,852 kWh in annual energy consumption. Hemp wool impacted wall, roof, and internal floor heat transfer by reducing them by 90.86% at 12,583 kWh, 85.1% at 6666 kWh, and 88.1% at −2664 kWh, respectively, while the discomfort degree hours were reduced by 17.6% at 9720.12. The outcomes provide patterns, explanations, and inferences that may be generalized to other projects in Burkina Faso, especially, and sub-Saharan African countries, in general, where most buildings are not well insulated. The availability of these bio-based and recycled insulation materials may also serve as proof to foster a circular economy in the Burkina Faso construction industry. Full article

Urban upgrading programs are implemented to enhance the living conditions in a city. However, the concept of to what extent the life of the targeted communities is improved remains contested and fluid. The purpose of this study was two-fold. First, it evaluated for the first time the indoor thermal conditions in the three main urban housing types in Kigali and analyzed whether the ongoing urban renewal takes into consideration occupant thermal comfort. Second, alternatives to improve thermal performance of urban housing were investigated and recommendations were given. Results indicate that modern urban housing performed significantly greater compared to other housing types, especially during daytime. Indoor thermal conditions in the planned low-income housing were no better—and, in fact, were slightly poorer—than in the informal settlement from which households were to be relocated. Through design parameter optimization, the indoor thermal conditions in the planned low-income housing were improved by 85.5% in the daytime hours and 71.2% in the nighttime hours. These findings are valuable to officials in resettlement programs by providing insights to improve urban dwellers’ living conditions from a wholistic prospective. This can assist related parties in mitigating project failure often caused by local resistance to resettlement. Full article

In this article, energy optimization of the cooling system of IKEA Budaörs is carried out. The cooling system is served by a centrifugal water chiller and includes a large-volume cooling buffer tank. The facility operates the hydraulic system of the buffer storage tank only during the transitional period. The main goal is to reduce energy consumption by changing the operating strategy of the existing system. To test the operating strategies, the operation and the thermal load of the shopping center during the summer season had to be simulated to find the best operation strategy. A hybrid method (real data and calculated values) was used in the simulation. The three operating scenarios examined show that the annual energy consumption and the number of operating hours of the chiller can be reduced by using the buffer tank with the right strategy. In the examined scenarios, a 30% energy improvement was achieved. The possibility of using a buffer tank is significantly limited by the fact that the heat exchangers were sized for low forward water temperatures. By re-sizing the heat exchangers, the utilization of the buffer tank could be considerably improved in conditions close to peak heat load. Full article

The energy consumption of existing buildings depends on their physical features, climatic conditions, and business activities, such as operating hours and occupancy characteristics. It is necessary to perform a fair assessment of building energy performance considering the business activities. It has become especially necessary to collect and manage information on business activities in hospitals since hospitals operate continuously throughout the year, treating patients and using various medical equipment. This study aimed to develop a benchmark that considers business activities and to perform building energy performance assessments in hospitals using the developed benchmark. Initially, the necessary data from hospitals for assessing energy performance and developing an energy benchmark were identified. Then, survey items regarding the business activities and energy consumption of buildings were designed, and a survey was conducted at 48 general hospitals. Secondly, multiple linear regression was used to identify and normalize the major business activities affecting energy use and to develop a benchmark for energy performance assessment. Thereafter, the Energy Efficiency Ratio (EER), the result of comparing the actual energy consumption with the benchmark, was used as an index for the energy performance assessment. Thirdly, additional general hospitals were surveyed to validate the benchmark. The EER of the additional surveyed hospitals was calculated with the developed benchmark. The Energy Use Intensity (EUI) and EER of buildings were reviewed, and analysis was performed to identify why some buildings had a similar EUI but a different EER. Finally, a method to improve the benchmark is presented, and the improved benchmark model is compared with the existing model. Full article

As fully prefabricated wood walls (FPWW) are envisioned to increase building envelope performance, the junction between panels becomes crucial. Since FPWW restricts access to the inter-panel joints, it is preferable to generate an upstream mechanism to complete the joint automatically on-site. This study aimed to design a self-sealing joint for FPWW that would achieve high energy standards and accelerate on-site construction. Airtightness tests and thermal bridge assessments were conducted in the laboratory to compare the developed self-sealing joints with different sealing materials. These same tests were conducted on-site, in addition to observations of the assembly speed of conventional prefabricated walls and FPWW. Of all the materials tested, butyl tape showed the tightest connections. This material helps the joint developed to automatically seal adjacent walls spaced up to 7 mm apart. FPWW maximize the industrialization of conventional prefabricated walls by realizing the sealing details and the installation of doors, windows and exterior siding offsite. This way, FPWW could reduce the duration of a conventional single-family residential project. FPWW maximize quality control while reducing transportation costs associated with conventional modular solutions. Full article

The performance of air conditioning systems deteriorate due to the natural aging and wear caused by operating the devices. This is termed “aging degradation,” and it results from a lack of appropriate maintenance which accelerates the degree of performance degradation. The performance degradation of an air conditioning system can cause problems such as increased energy consumption, deteriorated indoor heating environment, and shortened lifespan of air conditioning equipment. To prevent such problems, it is important to establish a long-term maintenance plan to recover degraded performance, such as predicting an appropriate maintenance time by identifying the real-time performance degradation rate based on a system’s operation data. In this study, the performance degradation rate, according to the operating time, was estimated using long-term operation data for devices constituting a heat source system, and the effect of performance degradation of the heat source system’s operation and energy consumption was reviewed using a simulation. The performance degradation rate of the target device was estimated by analyzing the variation trend of the calibration coefficient, which was calculated when the initial performance prediction model was calibrated through operating data. Using this approach, it was confirmed that the annual performance degradation rate was 1.0–1.4% for the heat source equipment, 0.4–1.2% for the cooling towers, and 0.8–1.3% for the pumps. In addition, a heat source system energy simulation calculated the 15-year performance degradation of the heat source equipment to be 34–52% and 7–19% for both the cooling towers and pumps. Due to the equipment performance deterioration, the number of operating heat source equipment and cooling tower fans, and the pump flow rate gradually increased every year, thus accelerating the performance deterioration even further. As a result, energy consumption in the 15th year increased by approximately 41% compared with the initial energy consumption. Full article

Heat gains and losses via building envelopes are impacted by varied characteristics such as geometry, orientation, properties of the building materials, and the type of construction and its interface with the exterior environment. Current studies are investigating the use of phase change materials (PCMs) characterized by high latent heat and low thermal conductivity that may cause temperature time lag and reduce amounts of heat transferred through building envelopes. The prime objectives of this research are evaluating zones’ energy consumption by type for an educational facility in a dry arid climate, examining the effects of a PCM (RT28HC) and polyurethane insulating material, comparing these effects to the existing situation with respect to cooling energy savings and CO₂ emissions, and studying the effect of varying PCM thicknesses. The working methodology depended on gathering the real status and actual material of the building, constructing models of the building using Design Builder (DB) simulation software, and comparing the insulation effect of incorporating polyurethane and phase change insulating materials. A parametric study evaluated various PCM thicknesses (6, 12, 18, 24, 30, and 36 mm). Validation was performed primarily for a selected year’s energy usage; simulation results complied with field measurements. The results revealed that an 18 mm PCM had a high efficiency regarding thermal comfort attributes, which reduced cooling energy by 17.5% and CO₂ emissions by 12.4%. Consequently, this study has shown the significant potential of PCM regarding improved energy utilization in buildings. Full article

The Kingdom of Saudi Arabia is working to establish cities based on the economy and attract investments such as Neom and The Line. Moreover, at the beginning of 2021, the Saudi government announced that it will stop dealing with foreign companies that establish regional offices outside the country, starting from the beginning of the year 2024. These acts will contribute to strengthening the presence of office buildings significantly. However, the biggest challenge is the inefficient energy design and operation of the existing office buildings in an overheated environment. Therefore, improving the thermal performance of existing office buildings has become a priority for sustainable development. This study aims to evaluate the current scenario of energy performance in Saudi governmental office buildings. One of the most important strategies of the Kingdom’s vision 2030 regards energy conservation. In support of the aim of this research, the annual electric energy bill of the Agricultural Development Fund building in Najran has been collected and analyzed. Accordingly, the analyses were carried out to evaluate the improvement in energy consumption through retrofitting the building envelope. DesignBuilder simulation program was used to investigate the effects of different retrofitting strategies of the building envelope in terms of changing the type of window’s glass, adding thermal insulation layers, and applying egg-crate shading devices. The results reported that applying a combination of those strategies reduced total energy consumption by 26.81% compared with the current base case. Full article

Wall-mounted solar chimneys use solar radiation to heat the air inside the chimney cavity and use thermal pressure to create natural convection. Applying this principle allows for the indoor ventilation of a building without energy consumption. However, in wall-mounted solar chimney designs, different air inlet and outlet design dimensions can have varying degrees of impact on the effectiveness of wall-mounted solar chimney ventilation. In order to analyze the internal airflow state and airflow temperature field distribution of wall-mounted solar chimneys, physical models of wall-mounted solar chimneys with six different air outlet-to-inlet cross-sectional area ratios were developed in this research work. Before numerical simulation analysis, heat transfer analysis of the wall-mounted solar chimney’s structural components and airflow channels was carried out, and corresponding mathematical heat transfer models were established. The internal flow state and temperature distribution characteristics of a wall-mounted solar chimney were analyzed by steady-state simulations using the computational fluid dynamics software, Ansys Fluent. Finally, transient simulation calculation analysis was conducted under six different S-value models to investigate the variation in the natural ventilation of a single-story building’s wall-mounted solar chimney for a whole day. The study showed that under the same simulation conditions, 80% ≤ S < 100% effectively avoided the formation of vortices in the internal airflow of the wall-mounted solar chimneys and kept the ventilation effect of wall-mounted solar chimneys at a high level. The results of this study provide a reference for the optimization of research on the design of the air inlet and outlet structures of wall-mounted solar chimneys for single-story buildings. Full article

Understanding how energy is used and where it can be saved in an existing building is critical not only from a cost and environmental standpoint, but for legal compliance as well, as the United States and the rest of the world increasingly have set tighter restrictions on energy usage and carbon emissions. Energy savings can be achieved from installing LED lights and occupancy sensors; however, the exact savings and impact of each method can vary depending on the building in question. The objective of this case study is to perform analysis of the lighting systems in Washington State University Tri-Cities’ Floyd & East buildings to determine energy savings potential. Lighting systems in each building were broken into several groups based on their operational patterns and then numerically modeled with the aid of Python. The results of this case study shows that 60% energy savings, totaling 350 MWh in a year, can be achieved by retrofitting fluorescent lights with LEDs and occupancy sensors. This energy savings translates to a reduction of 62.4 t of CO${}_2$ emissions per year. The results of our cost-analysis in this model shows that the LED light retrofit has a break-even point at 15 months of operation. Full article

Previous studies have been conducted by employing various methods to reduce the condenser water temperature, a crucial control variable to consider when attempting to improve the operational efficiency of a chiller. The existing literature dealing with the effects of low-condenser water temperatures is limited, as the cooling water flow rate is often considered the operating variable of the condenser loop. However, to produce additional low condenser water temperatures, the approach temperature of the cooling tower in the system must be reduced. To reduce the approach temperature, it is necessary to review the physical behavior and efficiency of the cooling tower according to the change in the liquid to gas ratio (LGR), which is dependent upon the condenser water flow rate and the cooling tower fan air flow rate within the condenser loop. However, this process has rarely been reviewed in previous studies. Therefore, this study developed a new cooling tower control algorithm from the LGR perspective, and the operational effectiveness was quantitatively reviewed using EnergyPlus. Compared to the conventional conditions, when the cooling tower operation algorithm for low-approach temperatures was applied, the annual energy saving was 27.0%, the average chiller COP was improved by 27.8%, and the average system COP was improved by 47.4%. Furthermore, even when the algorithm was not applied at the same condenser water set temperature, the annual energy saving was 15%. The average COP of the chiller and COP of the system is improved by 2% and 23.2%, respectively. These results indicated that when a cooling tower is operated with a low LGR, even under the same outdoor air and load conditions, the cooling system’s efficiency can be improved with a change in the control algorithm without installing additional high-efficiency equipment. Full article

In hospitals, operating rooms are energy-intensive spaces, due to the high flow of outside air required to achieve the necessary indoor air quality. Operating rooms demand ventilation continuously, despite periods of low daily surgical activity. However, by controlling ventilation during inactive periods in the operating room, significant energy savings can be achieved, avoiding penalties on IAQ levels. This paper evaluates the energy savings achieved by introducing ventilation flow control and regulation systems in operating rooms of hospitals located in different climatic zones within Spain. In addition, emissions and economic savings have also been evaluated. Two control and regulation strategies of the air flow to be supplied and extracted in the operating rooms, during periods of inactivity, are studied and include regulation by schedule and regulation by occupancy. Data from a 900-bed university hospital center are used as a reference to evaluate the average occupancy of the operating rooms, and the energy consumption, thus validating the model for calculating the demand of a typical operating room. The energy savings for the regulation by occupancy are 37.5%, and the regulation by schedule are 40% of the annual demand, with respect to an operating room working permanently. Full article

The COVID-19 pandemic forced higher education institutions to switch to online learning for most of 2020 and 2021 for the safety of their students and staff, which significantly impacted campus resource consumption. This study aims to analyze the changes in electricity consumption in higher education buildings based on comparisons of three academic years to understand more about the energy implications of the post-COVID-19 era. The electricity data were collected from 181 samples of the electricity meter records at Chulalongkorn University, Thailand. When compared to the typical academic year in 2018, the results indicate that electricity consumption in 2019 and 2020 decreased by 20.92% and 35.50%, respectively. The academic and the library-type buildings marked the biggest change in electricity reduction. The smallest change was found in the research type as its essential work remained on campus. Only electricity consumption in the residence type increased due to the long periods of online learning policies. Finally, the findings suggest that teaching and learning activities have a strong influence on electricity consumption in higher education buildings. The facilities and learning methods related to these activities should be carefully discussed as elements of an effective strategy to manage electricity demands at the university level. Full article

The implementation of building retrofitting processes targeting higher energy efficiency is greatly influenced by the investor’s expectations regarding the return on investment. The baseline of this work is the assumption that it is possible to improve the predictability of the post-retrofit scenario, both in energy and financial terms, using data gathered on how a building is being used by its occupants. The proposed approach relies on simulation to estimate the impact of available energy-efficient solutions on future energy consumption, using actual usage data. Data on building usage are collected by a wireless sensor network, installed in the building for a minimum period that is established by the methodology. The energy simulation of several alternative retrofit scenarios is then the basis for the decision support process to help the investor directing the financial resources, based on both tangible and intangible criteria. The overall process is supported by a software platform developed in the scope of the EnPROVE project. The platform includes building audit, energy consumption prediction, and decision support. The decision support follows a benefits, opportunities, costs, and risks (BOCR) analysis based on the analytic hierarchy process (AHP). The proposed methodology and platform were tested and validated in a real business case, also within the scope of the project, demonstrating the expected benefits of alternative retrofit solutions focusing on lighting and thermal comfort. Full article

Environmental degradation is significantly influenced by the construction industry. Energy-efficient retrofitting of existing office buildings has become an effective means of reducing building energy consumption. Implementation of retrofits requires the support and cooperation of stakeholders. However, existing studies on the dynamics of decision-making behavior among stakeholders are still relatively limited. This study constructed a tripartite evolutionary game model including the government, property owners, and end users, to better understand the behavioral evolution and evolutionary stabilization strategies of stakeholders. The results show that: stakeholders’ decision-making behavior has obvious mutual influence; benefits and costs are the dominant factors in stakeholders’ decision making; the effects of government supervision policies depend on the profitability of the project; and government behavior appears to be influenced by public willingness. In addition, targeted countermeasures were proposed for the development of the energy-efficiency retrofit market. This study provides a generic model that fits various contexts and can be used to inform a reference for scientific decision making by stakeholders. Full article

The building sector is responsible for more than one-third of total global energy consumption; hence, increasingly efficient energy use in this sector will contribute to achieving carbon neutrality. Most existing building-energy-benchmarking methods evaluate building energy performance based on total energy use intensity; however, energy usage in buildings varies with the seasons, and as such, this approach renders the evaluation of cooling and heating energy difficult. In this study, an information gain-based temporal segmentation (IGTS) method was used to identify the seasonal transition times based on patterns of hourly weather and corresponding building energy use. Twelve commercial buildings were considered for the study and four seasons were identified using IGTS; base-load, cooling energy, and heating energy data were gathered. For the 12 buildings, the estimated and measured heating and cooling energy during the summer and winter periods showed a linear relationship (R² = 0.976), and the average of those differences was 9.07 kWh/m². In addition, differences in the benchmarking results based on these energies were marginal. The results indicated that the IGTS approach can be effectively used for determining the actual heating and cooling energy consumption in buildings, as well as for energy benchmarking. This can, in turn, improve building energy use, with positive implications for achieving carbon neutrality. Full article

Recently, emissions and the energy use of the building and construction sector globally increased. Therefore, energy retrofit processes and reducing the energy consumption of buildings are increasingly often discussed by the academic community, industry, and end-users. The application of high-performance technologies and highly insulating materials results in a low energy demand in newly constructed buildings. A crucial challenge is to reduce energy consumption in existing buildings. The article presents an energy analysis of the reconstruction of a historic building adapted to hotel functionality. Based on the available information on the design of the facility, and the annual demand for cooling and heating energy, simulations of the energy performance were carried out. The proposals to exchange the heat source and replace the existing systems were simulated and assessed. Three different retrofit options were analyzed, including the replacement of the air handling unit (variant 1—v1), bathroom fixtures (v2), and, in the last scenario analyzed (v3), the above-mentioned activities and the usage of tri-generation units. As the results show, such solutions allow for the reduction in final energy consumption of 20%, to 73% regarding the baseline variant. Full article

The energy industry has been trying to reduce the use of fossil fuels that emit carbon and to proliferate renewable energy as a way to respond to climate change. The attempts to reduce carbon emissions resulting from the process of generating the electric and thermal energy needed by a building were bolstered with the introduction of the concept of nZEB (nearly zero-energy building). In line with such initiatives, the South Korean government made it mandatory for new buildings to have an nZEB certificate as a way to promote the supply of renewable energy. The criteria for Energy Independence Rate, which is one of the nZEB certification criteria in South Korea, is to maintain the share of renewable energy as at least 20% of the primary energy sources for the building. For a new building in South Korea to have an nZEB certificate, it is required to establish an energy plan that would allow the building to meet the Energy Independence requirement. This optimally reflects the cost of installation for renewable energy facilities and the cost of purchasing energy from external sources, such as the national grid or district heating companies. In South Korea, the base retail rate of energy is calculated based on the peak demand per hour over the year, rather than the contracted energy. This has produced difficulties in standardizing the process with a mathematical model; in addition, there have not been many preceding studies that could be used as a reference. In this regard, this paper analyzed a modeling strategy for developing a realistic yet optimized energy plan in consideration of the unique conditions of the retail energy rates of South Korea, and analyzed the impact of the rates based on peak demands upon the total energy plan. In this study, our research team analyzed the electric billing system, conducted a case study, and analyzed the impact of the billing system that is based on the peak demand upon the optimal cost. By utilizing the restrictions for reaching the 20% Energy Independence goal, this paper calculated the proper energy supply facility capacity for renewable energy. Then, the cases in which the maximum demand modeling was used and the cases without one were compared to confirm the cost benefits observable when the suggested model is added or implemented. Full article

Utilities are increasingly interested in integrating energy efficiency and demand response measures as a strategic approach that aims to achieve an increasingly reliable, dynamic, and integrated electric system. The concepts of energy efficiency (EE), demand response (DR), and system reliability (ESR) have been mainly studied from a different perspective, dealing only with the interaction between EE and DR and between EE and ESR. This paper aims to improve knowledge and demonstrate the validity of EE interventions (EEIs) through the use of a tool for evaluating the benefits of energy efficiency measures (EEMs) in the environmental sphere and in terms of DR and ESR. In order to evaluate this interaction, a quantitative method is proposed and validated on real results in an Italian case scenario, taking into account the analysis of smart meters data for residential users located in southern Italy in Calabria. Based on the collected data, an aggregation of users was evaluated with real hourly profiles covering the period from January 2020 to August 2020. These results show how efficient energy use may affect DR resource availability and power systems reliability. In conclusion, the authors justify that a more reliable electric system is ready for new types of EE financing systems based on pay-for-performance contracts. Full article

With the promotion of the concept of sustainable development and green buildings, green building rating systems are beginning to emerge and gradually attract more attention. Leadership in Energy and Environmental Design (LEED) is a widely used and influential rating system worldwide, and research on it has shown an increasing trend year by year. To establish a comprehensive understanding of the LEED research field, this article visualizes and analyzes the LEED research literature by CiteSpace to obtain journal, author, institution, and country collaboration networks, reference co-citations and clusters, keyword co-occurrence networks and citation bursts. The study found the relationships among journals, authors, institutions, countries, research frontiers, research hotspots, and research processes in the field of LEED research. A framework of the knowledge system of LEED research was constructed based on these findings to present the current status and future trends and provide a reference for future research. Full article

Intelligent building management systems are proven to lead to energy savings and are an integral component of smart buildings. The procedures developed in the EN standards describe the methodology for calculating the energy savings achieved by improving the automation and control levels of separate services in building systems. However, although this method is used in practice, it is rarely applied or investigated by the research community. Typically, energy savings resulting from a single automation improvement intervention in a building heating system are observed, while the holistic view of combined automation upgrades is not considered. Therefore, the purpose of this study was to assess the energy savings resulting from several upgrades to control levels in the heating system components of the building. In addition, this research provides a rationale for the impact of multiple automation and control options for heating systems as well as examines the difference in energy savings. Finally, an analytical model is developed and demonstrated to assess the feasibility of building automation and control upgrades, by determining the allowed investment according to a set of predefined indicators. Full article

While externally insulated wall assemblies are widely recognized for their hygrothermal performance, few research projects have focused on the impact of shifting the entire wall insulation to the exterior side of a structural cavity in cold or subarctic climates or its effectiveness in terms of acoustic performance and airtightness. The objective of this study was to propose fully externally insulated assemblies that could be used in cold and subarctic climates by assessing the benefits of the hygrothermal performance of these assemblies and by achieving a comparable airtightness and sound transmission performance to the modern assemblies that are currently built in North America. The results suggested that the externally insulated assemblies limited the risk of condensation occurring inside structural cavities and allowed for faster drying than the modern assemblies when exposed to water infiltration or high water contents in all climates that were tested. The assemblies with external airtight insulation boards were more airtight than assemblies with air barrier membranes and, in addition, assemblies with external soundproof insulation were shown to be necessary to achieve a comparable sound transmission loss to that of a modern assembly. Full article

Energy consumption in the building sector is a major concern, particularly in this time of worldwide population and energy demand increases. To reduce energy consumption due to HVAC systems in the building sector, different models based on measured data have been developed to estimate the cooling load. The purpose of this work is to develop a linear regression model for cooling load of a research room based on the radiant time series (RTS) components of the cooling load that consider the building material and the environment. Using the forward step method, linear regression models were developed for both all-seasons and seasonal data from three years of cooling load data obtained from the RTS method for a research room at Mangosuthu University of Technology (MUT), South Africa. The male and female occupants, window cooling load, and roof cooling load were found to be the most influential predictors for the cooling load model. The obtained relative errors between the best all-seasons model and seasonal models built with the same predictors for the respective data subsets are almost zero and are given as 0.0073% (autumn), 0.0016% (spring), 0.0168% (summer), and 0.0162% (winter). This leads to the conclusion that the seasonal models can be represented by the all-seasons model. However, further study can be performed to improve the model by incorporating the occupancy behaviours and other components or parameters intervening in the calculation of cooling load using the radiant time series method. Full article

In the European Union, only 1% of the building stock is renovated every year. According to the EU strategy, around 75% of the existing building stock needs to be renovated by 2050. Energy efficiency programs mainly support residential and public building stocks; this article considers military dormitories as a type of unclassified building. It is very important to improve energy efficiency to reduce energy consumption and improve the microclimate in these buildings, since the staff is there 24/7. This paper analyzes the energy consumption and measures the indoor air quality in 13 nonrenovated military dormitories. The personnel in unclassified buildings have limited options for remote work in the case of COVID-19 outbreak. Thus, the retrofitting and maintenance of such buildings must be planned carefully. There is a significant lack of IAQ measurements in unclassified buildings. This study presents a wide analysis of energy consumption, indoor air parameters, and occupant satisfaction. On the basis of real data, four retrofitting scenarios were evaluated in IDA ICE dynamic simulation software. The simulation results showed that, in the case of a deep renovation scenario, the theoretical energy savings could be 77.6–79.3% of the used energy. This paper discusses the solar energy potential of onsite energy production for increasing the efficiency and energy supply resilience of unclassified buildings. The results of this study can be applied to other countries with climate conditions similar to Latvia. Full article

Domestic hot water heating of multifamily buildings accounts for a substantial portion of the energy load of existing buildings. This load is made up of both the energy required to produce hot water and the energy needed to maintain the temperature of the heated water within a building’s distribution piping so that heat can be promptly delivered to building occupants as needed. Properly designed heat pump water heater (HPWH) systems have the ability to improve efficiency in both water heating and temperature control operations. Further, CO₂ heat pump technology reflects a shift away from traditional refrigerants and toward refrigerants with low global warming potential (GWP). In this paper’s case study, a design consisting of multiple CO₂ heat pump water heaters (commonly used in single-family homes) with a novel “swing tank” was proposed to meet the demand for domestic hot water heating and recirculation loop temperature maintenance. The proposed design was applied to the retrofit of a 60-unit, low-rise, multi-family building located in the Pacific Northwest of the United States. The purpose of this paper is to verify the performance of the system including the proposed “swing tank” in a centralized SHW system using CO₂ HPWH. It also provides practical information and lessons learned from the retrofit project. Long-term monitoring data showed that the system had a coefficient of performance (COP) of three or greater and provided an average of 20 gallons of hot water per day per apartment. The results of this work indicate that residential-scale CO₂ HPWH equipment and a “swing tank” design can efficiently provide domestic hot water heating and temperature maintenance for mid-sized multifamily buildings. Full article

The building envelope design constrains how much HVAC systems must work to provide comfort. High thermal mass in walls is preferable to delay heat gain, as well as reduce it. Phase Change Materials (PCMs) seem to proportionate more thermal mass without increasing wall thickness because of their high latent heat. Thus, this work studies various PCM-based envelope layouts in four case studies, H060, H100, H200, and OB, under the tropical climate of Panama City, via building energy performance simulation. Energy and thermal comfort performance were used as criteria to determine an optimal PCM-based layout for such a climate through optimization analysis and to compare PCM-based and non-PCM-based envelope layouts. Results showed that among the considered combinations, PCM-based roof configurations provide more optimum solutions than PCM-based wall configurations. The PCM layout with a melting temperature of 27 °C allowed completion of the PCM cycle throughout the year. Although other PCM layouts did not present a complete charge/discharge cycle, such as the most frequent options at H060, H100, and H200, it suggests that PCM on liquid or solid phase provides better thermal performance than other considered combinations. Full article

The Chinese government has taken actions to promote energy efficiency through the renovation of residential buildings in the Northern Heating Region. Homeowners have been encouraged to undertake government-led energy efficiency renovation; however, their decisions to undertake the renovation are affected by several barriers. The lack of participation from homeowners has brought difficulties in execution and financing. This study empirically investigated the barriers facing homeowners when undertaking the renovation, including barriers generated from the homeowner’s cognitive biases. The results show that barriers associated with capital cost, unbalanced financial plan, unclear process, comfort, and increased energy prices are the most widely considered when homeowners make decisions about undertaking renovation projects. An adverse decision is most likely to be generated when: (1) when homeowners perceive the financial plan as unfair, (2) when they have already done renovation at their own expense, or (3) when they have the feeling of losing initiative. Among all the individual factors, the homeowners’ gender, age, education level, and building type are significant in predicting their decisions. By drawing on insights from behavioral economics, we analyzed the mechanisms behind these barriers. The findings can help policymakers to design more cost-effective policy instruments to mitigate the barriers. Full article

The envelope (façade) of a building is the part that forms the primary barrier to its environment. Most of the new and modern office buildings have a glazed envelope and are usually built-in city centers. The concept of a double-skin façade was born as a consequence of urban noise. The principal noise source in urban areas is traffic noise. Using a double-skin façade can be a solution that ensures good sound insulation for a glazed office building. This study presents experimental results obtained both from measurement campaigns carried out over longer periods of time, in connection with heat transfer in the case of this system, and punctual measurements, over shorter periods of time, for sound insulation and interior comfort parameters, from the experimental chamber adjacent to the system. The results from this study indicate that box double-skin façades can contribute to noise reduction, improve the interior thermal comfort and increase the energetic performance compared to normal single-glass façades, but within certain limits. Full article

Owing to the high energy consumption in the building sector, appraising the thermal performance of building envelopes is an increasing concern. Recently, a few in situ methodologies to diagnose the thermal parameters of buildings have been considered. However, because of their limitations such as low accuracy, limited number of measurements, and the high cost of monitoring devices, researchers are seeking a new alternative. In this study, a novel hyper-efficient Arduino transmittance-meter was introduced to overcome these limitations and determine the thermal parameters of building envelopes. Unlike conventional methodologies, the proposed transmittance-meter is based on synchronized measurements of different parameters necessary to estimate the transmittance parameter. To verify the applicability of the transmittance-meter, an experimental study was conducted wherein a temperature-controlled box model was thermally monitored, and the outputs of the transmittance-meter employed were compared with those captured by a commercial device. The results revealed a high level of reduction in cost and a low range of difference compared with the latter, thereby validating the applicability of the proposed thermal monitoring system. Full article